In April, Lady Thatcher's son was refused a visa to join his wife and children in the US, where he intended to start a new life.
Originally, he blamed his conviction for inadvertently bankrolling an attempted coup in Equatorial Guinea, saying: "It was always a calculated risk when I plea-bargained in South Africa."
However, a new biography Thatcher's Fortunes claims otherwise. It says that - regardless of that affair - Sir Mark was already considered too dodgy to live in the US.
"If Thatcher had asked for a temporary or a multi-entry visa for brief holidays, he'd have been fine," a US State Department official told the author Mark Hollingsworth.
"But the arrogant idiot applied for a permanent residency, which meant there was a full-blown inquiry. They turned up all the IRS files on his lawsuits in the 1980s. That was the problem, not the recent criminal conviction in South Africa."
Either way, the setback cost Sir Mark a heavy price. He subsequently split from his wife, Diane, after 18 years and moved in with his mother in Belgravia.
Since then, he's said to have gained a new lady friend, Lord Rothermere's sister-in-law, Lady Francis Russell, and adopted a working-class accent.
"It makes him sound like an Old Harrovian Arthur Daley," reports Hollingsworth.
* Jude Law can be fairly described as a "love rat" after bonking his children's nanny, Daisy Wright, behind the back of on-off girlfriend Sienna Miller.
Woe betide anyone impertinent enough to suggest that the whole grotty business might have, in some way, damaged his acting career, though.
The frisky matinée idol is taking legal action against The Sunday Times over a news article published nine days ago under the headline: "Studios snub Jude Law as scandals tarnish name".
Among other things, Law is upset at the newspaper's suggestion that Sony has delayed releasing his new film, All the King's Men - and stopped backing it for an Oscar - due to its star's tangled love life.
Sources close to the star, who is represented by the libel lawyers Teacher Stern Selby, say he's prepared to fight this one "all the way".
Meanwhile, the newspaper confirms that they've received a lawyers' letter, but are yet to decide how to respond.
* Under the snappy headline "Help!", a Sunday newspaper claimed that John Lennon's son, Sean, has split from his glamorous 18-year-old girlfriend, Anouska Beckwith.
This comes as news to Anouska's socialite mother, Tamara, whom I bumped into yesterday. "That's total and utter nonsense," she said. "They are both very happy, and in fact just spent the weekend in the country, with Sean's mother, Yoko Ono."
Ms Beckwith is delighted that the liaison of 30-year-old Lennon with Anouska, a drama student, has entered its fourth month. She can think of no more splendid prospect than one day being related to the colourful and charming Yoko Ono.
* Tony Blair's recent wobble has once more dangled the prime ministerial carrot in front of Gordon Brown's hungry chops.
The Chancellor of the Exchequer makes a two-day visit to Israel this week on EU business. It has been noted in Downing Street that, for this somewhat routine trip, he is being accompanied by not one, not two, but three different camera crews.
"Every time Gordon gets a foreign tour, his spin-machine is desperate to put it on TV," complains one Blairite.
"It was the same last year, when he did all that bleeding heart stuff in Africa. You couldn't move for cameramen.
"Gordon reckons glad-handing world leaders makes him look like a prime minister in waiting. We think it makes him look out of his depth. Scottish people get sunburnt far too easily."
* Jeremy Clarkson - gentleman and controversialist - has never been short of left-wing critics. But it has surely come to something when the green lobby decides to "name and shame" him in Parliament.
An Early Day Motion, submitted by two Liberal Democrat MPs, complains of the Top Gear presenter's "curious and misguided attitude" to "the real and major threat posed by climate change".
The motion also demands that Clarkson is hauled before MPs to explain himself. Yesterday, Norman Baker, one of its authors, explained: "I don't want to limit his free speech, and I don't know if what he says is serious or a joke, but I am concerned that he is persuading people that climate change, which is very real, is not happening."
Asked if he'd like to meet Clarkson, Baker adds: "Yes, provided it's at a safe distance and he's not behind the wheel of a car."Reuse content